Recent research suggests that toothed whales possess anatomical specializations enabling lateralized register vibrations, contribute to a rich and complex vocal repertoire. Along with vocal learning abilities, this indicates that their communication systems may be among the most complex in the animal kingdom. However, the evolutionary processes shaping vocal repertoire complexity remain unclear due to the lack of standardized, quantitative analyses of their vocal signals. This study addresses that gap by examining the tonal sound repertoires of 15 toothed whale species representing major evolutionary lineages. Using acoustic data from the Watkins database and from the authors, 500 tonal contours were randomly selected per species. These were analyzed to generate measures of vocal diversity (Hill numbers), composition (contour types), complexity (modulation patterns), and acoustic structure (frequency and duration). Trait reconstructions using Maximum Likelihood methods were used to identify patterns of convergence and divergence across species. Preliminary results show that high-frequency, diverse, and complex repertoires are most common among Delphinidae species, especially those living in fission–fusion societies where vocal communication supports social cohesion. The study also accounts for sampling bias and missing data. These preliminary findings represent a first step toward reconstructing the macroevolutionary history of vocal repertoire traits in toothed whales.
May-Collado et al. (Wed,) studied this question.